1 files changed, 52 insertions, 0 deletions
diff --git a/src/libbio/bgetc.c b/src/libbio/bgetc.c
new file mode 100644
index 00000000..4c8ae90c
--- /dev/null
+++ b/src/libbio/bgetc.c
@@ -0,0 +1,52 @@
+#include	"lib9.h"
+#include	<bio.h>
+
+int
+Bgetc(Biobuf *bp)
+{
+	int i;
+
+loop:
+	i = bp->icount;
+	if(i != 0) {
+		bp->icount = i+1;
+		return bp->ebuf[i];
+	}
+	if(bp->state != Bractive) {
+		if(bp->state == Bracteof)
+			bp->state = Bractive;
+		return Beof;
+	}
+	/*
+	 * get next buffer, try to keep Bungetsize
+	 * characters pre-catenated from the previous
+	 * buffer to allow that many ungets.
+	 */
+	memmove(bp->bbuf-Bungetsize, bp->ebuf-Bungetsize, Bungetsize);
+	i = read(bp->fid, bp->bbuf, bp->bsize);
+	bp->gbuf = bp->bbuf;
+	if(i <= 0) {
+		if(i < 0)
+			bp->state = Binactive;
+		return Beof;
+	}
+	if(i < bp->bsize) {
+		memmove(bp->ebuf-i-Bungetsize, bp->bbuf-Bungetsize, i+Bungetsize);
+		bp->gbuf = bp->ebuf-i;
+	}
+	bp->icount = -i;
+	bp->offset += i;
+	goto loop;
+}
+
+int
+Bungetc(Biobuf *bp)
+{
+
+	if(bp->state == Bracteof)
+		bp->state = Bractive;
+	if(bp->state != Bractive)
+		return Beof;
+	bp->icount--;
+	return 1;
+}